The use of retractable writing implements such as pens, mechanical pencils and the like is well known and widely used. One beneficial form of retractable writing implement is the telescoping pen which has the advantage of reducing the length of the pen when not being used, and then easily extending the length while simultaneously exposing the writing point for use. For example, U.S. Pat. No. 6,474,889 issued to Kato (Nov. 5, 1982) discloses a telescoping pen employing, among a large number of components, a coil spring. Similarly, U.S. Pat. No. 6,273,627 issued to Muttersinker et al. (Aug. 14, 2001) discloses an expandable pen which extends the writing tip when the pen body is extended. However, the device also requires a coil spring and a large number of other mechanical parts, increasing the cost of manufacture, and reducing lifespan and reliability.
A published U.S. Patent application 20110129285 by Liu et al. discloses a retractable pen that simultaneously telescopes in length and extends or retracts the writing point, but this invention also employs a spring and has a large number of parts. The cost of manufacturing pens is highly dependent on the number of components and complexity. Moreover, the use of a coil spring not only adds cost but is subject to rusting and corrosion, shortening the life and reducing reliability of the writing device.
U.S. Pat. No. 4,266,881 issued to Rubens May 12, 1981) attempts to address the high cost and lower reliability of using a spring in a writing implement, but does not disclose a telescoping device, merely a retracting pen having more than one ink cartridge. No one has previously disclosed a telescoping writing implement that extends and contracts while simultaneously exposing and retracting the writing point, without the use of a spring mechanism.
U.S. Pat. No. 2,518,128 issued to Dufilho (Oct. 14, 1927) discloses a springless telescoping pen or pencil having gradations and at least one non-round side, but it does not provide for retracting the writing point inside a protective body.
U.S. Pat. No. 2,571,830 issued to Buell (Jan. 2, 1948) discloses a telescoping mechanical pencil in which relative movement of two pencil bodies advances the writing lead. However, the telescoping mechanism does not shorten the overall length, does not move the writing tip back into the pencil body and, further, requires a spring.
U.S. Pat. No. 8,087,841 issued to Liu Jan. 3, 2012) discloses a retractable pen with an extending pen body. However, this invention requires a large number of individual parts (18 individual parts are disclosed), including a coil spring. The mechanism and its assembly are necessarily complex, increasing the cost of manufacture and raising the number of potential points of failure.
There is also a need to reduce the diameter of pens to allow them to fit certain applications such as inserting into writing tablet bindings, and to make them more convenient for certain users.
It is therefore an object of this invention to provide a telescoping pen that conveniently extends its length while simultaneously exposing the writing end, and reducing its length while protectively storing its writing end.
It is a further object of the present invention to provide a telescoping pen apparatus that does not require a coil spring.
It is a further object of the present invention to provide a telescoping pen with a minimum number of component parts, reducing cost of manufacture and increasing lifetime reliability.
It is a further object of the present invention to reduce the diameter of the pen body by eliminating internal components that require excessive lateral space.